(a) Field of the Invention
The present invention relates to a thin film transistor array panel and a manufacturing method thereof, and in particular, to a thin film transistor array panel for a display device and a manufacturing method thereof.
(b) Description of the Related Art
Generally, a liquid crystal display (LCD) includes a thin film transistor (TFT) array panel including signal lines, pixel electrodes, and TFTs, a common electrode panel including a common electrode facing the pixel electrodes, and a liquid crystal layer disposed between the panels.
The pixel electrodes are driven by signals from the signal lines including gate lines and data lines that intersect each other to define pixel areas. The signal lines are connected to the pixel electrodes through switching elements such as thin film transistors (TFTs).
Each of the TFTs has a gate electrode connected to a gate line, a source electrode connected to a data line, and a drain electrode connected to a pixel electrode. The TFT is turned on in response to a gate-on voltage supplied from the gate line through the gate electrode and receives data voltages from the data line through the source electrode. The TFT then transmits the data voltage to the pixel electrode through the drain electrode to charge the pixel electrode.
When the TFT is turned off by a gate-off voltage supplied from the gate line, the voltage of the pixel electrode is abruptly dropped due to a kickback voltage. The kickback voltage has a magnitude depending on a parasitic capacitance between the gate electrode and the drain electrode of the TFT. The kickback voltage generates flickering on the images displayed by the LCD, and the flickering may be reduced by adjusting a voltage applied to the common electrode.
In the meantime, the signal lines, the pixel electrodes, the TFTs, etc. are usually formed by photolithography including light exposure.
When an active area on a backplane for the TFT panels is too large to use a pattern mask, the entire exposure is accomplished by repeating a divisional exposure called step-and-repeat process. One divisional exposure unit or area is called a shot. Since transition, rotation, distortion, and etc. are generated during light exposure, the shots are not aligned accurately. Accordingly, the parasitic capacitances between the gate electrodes and the drain electrodes differ depending on the shots, and this causes s the difference in the kickback voltages between the shots. The difference in the kickback voltages causes the difference in the luminance between the shots and deteriorating the flickering.